High speed method and apparatus for producing foundry molds

ABSTRACT

In the production of foundry mold parts by the method described in U.S. Pat. No. 3,739,834, the production rate is increased by employing a foundry sand mix which can be cured by means of a gaseous curing agent and carrying out curing of the pressed mold part while the mold part is supported at the pressing station.

BACKGROUND OF THE INVENTION

As disclosed in U.S. Pat. No. 3,739,834, issued June 19, 1973, in thenames of Kent Woonton et al., foundry mold parts are produced at a highproduction rate by forming a continuous bed of a curable foundry sandmix, advancing the bed to a pressing station, forming the mold part by apressing operation, and then curing the pressed mold part. Using a sandmix which retains adequate plastic flowability to be pressed over thetime required to advance the bed to the pressing station, the method hasheretofore required that the pressed mold part be moved away from thepressing station before being cured. The mold part is severed from thebed by the pressing operation and, for example, can be advanced to acuring station by the same mechanism employed to advance the bed of sandmix to the pressing station. As disclosed in U.S. Pat. No. 3,796,250,issued Mar. 12, 1974, in the names of Kent Woonton et al., it isadvantageous to employ an endless conveyor belt to carry the bed of sandmix to the pressing station and to carry the pressed mold parts to thecuring station.

While the method just referred to represents a substantial advance inthe art, room for improvement has remained. Thus, the requirement for aseparate curing station has tended to increase the overall apparatuscost and complexity, particularly when the nature of the curingoperation is such that mechanical movements at the curing station mustbe coordinated in precisely timed relation to mechanical movements atthe pressing station. Also, when the foundry sand mix is one which iscured by a gaseous curing agent, provision of a separate curing stationtends to require use of relatively large volumes of the curing gas.Another difficulty which must be faced when the mold part is cured in alocation separate from the pressing station is that the pressed but asyet not fully cured mold part must be moved without damaging the moldpart, a requirement which dictates a relatively expensive supportstructure as well as, in some cases, a slower cycle time.

OBJECTS OF THE INVENTION

A general object of the invention is to improve foundry mold partforming methods and apparatus, of the type referred to, in such fashionas to allow both higher production rates and lower apparatus costs.

Another object is to simplify such methods and apparatus by carrying outthe pressing and curing steps at the same station.

A further object is to eliminate from such methods and apparatus theneed for accomplishing mechanical operations, such as closing of acuring chamber, in highly precise timed relation to the pressingoperation.

Yet another object is to eliminate the need for moving the pressed moldpart while the mold part is still in a relatively fragile, largelyuncured state.

SUMMARY OF THE INVENTION

Broadly considered, method embodiments of the invention compriseestablishing on a movable support, typically an endless conveyor belt, abed of predetermined depth of a foundry sand mix which includes acurable binder material, moving the support to present the bed of sandmix at a forming station, laterally confining a portion of the bed andforcing a pattern into the laterally confined portion to press thatportion into the form desired for the mold part, and passing a gaseouscuring agent into the pressed portion of the sand mix while the same isstill laterally confined and still engaged by the pattern to therebycure the shaped mold part at least to such an extent that the mold partcan be moved and handled without breakage or significant deformation. Inespecially advantageous embodiments, the movable support is a foraminousconveyor belt and the step of passing the gaseous curing agent into theformed mold part is accomplished by passing the gas through the conveyorbelt into the mold part. Best results are obtained when the gaseouscuring agent is supplied in a volume and over a period of time such thatthe mold part can be taken directly from the forming station and used incasting, without further treatment. In all embodiments, the forming stepis completed before introduction of the gaseous curing agent commences,and the formed mold part is maintained laterally confined and inengagement with the pattern during the curing operation.

In order that the manner in which the foregoing and other objects areattained according to the invention can be understood in detail,particularly advantageous embodiments thereof will be described withreference to the accompanying drawings, which form part of the originaldisclosure hereof, and wherein:

FIG. 1 is a semi-diagrammatic illustration of apparatus for carrying outthe method acording to one embodiment of the invention;

FIG. 2 is a fragmentary sectional view, taken generally on line 2--2, ofFIG. 1;

FIG. 3 is a fragmentary sectional view, greatly enlarged as compared toFIG. 1, the view being taken through a small portion of a conveyor beltand support member forming part of the apparatus of FIG. 1;

FIG. 4 is a fragmentary sectional view taken through a shear bladeforming part of the apparatus of FIG. 1;

FIG. 5 is a view similar to FIG. 1 illustrating apparatus according toanother embodiment of the invention;

FIG. 6 is a view similar to FIG. 1 showing apparatus according to yetanother embodiment; and

FIG. 7 is a schematic diagram illustrating a modification of theapparatus of FIGS. 1 and 2.

GENERAL DESCRIPTION OF APPARATUS EMBODIMENT OF FIGS. 1-4

Before describing method embodiments, the apparatus embodiment of FIGS.1-4 will be described in order that the method can be understood morereadily. The apparatus is broadly similar to that described in U.S. Pat.No. 3,796,250 but without the separate curing unit. Thus, the apparatuscomprises a power driven endless belt 1 arranged so that the upper runof the belt extends horizontally and can convey a continuous bed 2, FIG.2, of foundry sand mix from a point of deposition (not shown) to theforming station indicated generally at 3. The upper run of the conveyorbelt is supported by stationary supports 4 before and after the formingstation and, at the forming station, by a heavy horizontal plate 5. Theforming or pressing apparatus comprises a rectangular shear box 6, twowalls of which extend transversely across the conveyor belt and theother two walls of which extend each along a different edge portion ofthe belt, all of the walls lying in planes at right angles to the planeoccupied by the upper run of the belt. Also included in the formingapparatus is a pattern carrier or platen 7 to which the pattern 8 isaffixed. The platen is carried by a movable support 9 guided by fourupright guide rods 10 and secured to piston rod 11 of a verticalhydraulic rectilinear power device (not shown) by which the pattern isforced downwardly into the sand mix bed. Shear box 6 is movablysupported by frame members 12 guided by rods 10. Two hydraulic powerdevices 13 are each connected to a different one of members 12. Powerdevices 13 are mounted on and depend from the support block 14 whichcarries plate 5, the arrangement being such that simultaneous operationof power devices 13 to retract the piston rods 15 thereof is effectiveto drive shear box 6 downwardly into engagement with belt. Such downwardmovement of the shear box is independent of platen 7 and is effective toforce the walls of the shear box through the bed 2 of sand mix and thuslaterally confine a predetermined rectangular body of the sand mix. Fromcomparison of FIGS. 1 and 2, it will be seen that shear box 6 iscentered above plate 5 and is of such size and plan configuration thatthe lower edges of all four walls of the shear box oppose the upper faceof plate 5. Power devices 13 are operated to lower the shear box intoengagement with the belt preparatory to the pressing step, i.e., beforeplaten 7 is driven downwardly.

Advantageously, conveyor belt 1 is a stainless steel belt provided witha large number of small apertures 16, FIG. 3. Typically, the stainlesssteel belt can be 0.508 mm. thick, with the apertures 16 being circularand having a diameter of 0.8 mm., with there being 36 apertures persquare cm., yielding an effective porosity of approximately 20% on atotal area basis.

Plate 5 is rigidly mounted in centered relation below the formingapparatus and is rectangular in plan and so dimensioned that the plateextends beyond the confines of shear box 6. Plate 5 is provided with aplurality of horizontal bores 17 each of which communicate, as seen inFIG. 3, with a plurality of vertical bores 18. All of bores 18 openupwardly through the upper face 19 of plate 5, bores 18 being uniformlydistributed throughout the rectangular area defined by the walls ofshear box 6 when the shear box engages belt 1. The diameter of each bore18 is large in comparison to the diameter of apertures 16 so that, asseen in FIG. 3, each bore 18 always communicates with a plurality of theapertures 16 of belt 1 regardless of the position of the belt during itstravel over plate 5. Thus, bores 18 can typically have a diameter ofapproximately 6.3 mm. when the diameter of apertures 16 is 0.8 mm.

Each bore 17 is connected to a conduit 19, FIG. 1, which in turn isconnected to a manifold 20.

Manifold 20 is connected via a pressure reducing valve 21 and an on-offvalve 22 to an accumulator 23 which is supplied with the gaseous curingagent via a second pressure reducing valve 24 from a pressure tank 25.

With the gas pressure in tank 25 typically being 650-750 p.s.i.(45.7-52.7 kg. per sq. cm), pressure reducing valve 24 allowsestablishment of a large volume of gas in accumulator 23 at a relativelylow pressure of, e.g., 60-70 p.s.i. (4.2-4.9 kg. per sq. cm.), andpressure reducing valve 21 allows a high gas flow rate at a workingpressure of, e.g., 2-10 p.s.i. (0.14-0.7 kg. per sq. cm.).

Conveyor belt 1 is driven stepwise by any suitable drive mechanism, suchas that disclosed in U.S. Pat. No. 3,796,250, in such fashion that eachstep of movement of the belt 1 will move the leading edge 2a, FIG. 2, ofthe bed of sand mix to a position aligned with the surface of wall 6a ofthe shear box which faces the advancing bed, it being understood that,by action of power devices 13, the shear box 6 is raised to a positionabove the sand mix bed before the belt is operated. After each step ofmovement of the belt, devices 13 are operated to drive shear box 6downwardly against the belt, and platen 7 is then driven downwardly bypiston rod 11 to force pattern 8 into the body of sand mix confined bycoaction of the shear box and belt. The curing gas is then supplied tothe pressed mold part 26, via conduits 19, bores 17 and 18, andapertures 16, to cure the mold part. Then, after valve 22 has beenclosed, piston rod 11 is raised to remove the pattern from engagementwith the mold part, power devices 13 are operated to raise the shear boxabove the level of the sand bed, and belt 1 is advanced again to removethe completed mold part 26 from the pressing station and bring theleading portion of the sand mix bed 2 into position at the pressingstation, as will be apparent from FIG. 2.

As seen in FIG. 4, the lower edge of each wall of the shear box 6 isadvantageously provided with a downwardly opening groove accommodating asealing strip 27 to form a relatively fluid-tight seal with belt 1 andthus minimize escape of curing gas from the shear box at the face of thebelt. Escape of gas from the shear box is thus concentrated at theslidably engaged surfaces of the shear box and platen 7, and the leadingportion of sand mix bed 2 upstream of the pressing station is notsignificantly affected by the curing gas.

When the pattern is to be heated, platen 7 is provided with bores eachaccommodating a conventional electrical cartridge heater 28, FIG. 1.

When relatively high rates of belt travel are employed, the metal belt 1can be provided with a polymeric facing to afford additional frictionalengagement between the belt and the sand mix.

Though perforated metal belts are particularly advantageous, woven beltsof equivalent effective porosity are also suitable. For example, aconventional 2-ply, center bound, woven, untreated cotton belt 0.24 mm.in thickness and an average weight of approximately 1.25 kg. per 30meters of length per 2.5 cm. of width has been successfully employed. Ingeneral, the porosity of the belt should be at least 15%, on a totalarea basis, to allow good gas flow rates into the pressed mold part.

GENERAL DESCRIPTION OF THE METHOD

The apparatus of FIGS. 1-4 is typical for carrying out the method.

The bed 2 can be formed continuously from a uniform mixture of foundrysand and any of the suitable binder formulations which can be cured witha gaseous curing agent. Thus, the binder material can be of the phenolicresin-polyisocyanate type, curable with gaseous tertiary amines such astrimethylamine or with liquid amines such as trimethylamine dispersed ina carrier gas such as nitrogen; or of the furfuryl alcohol-formaldehydetype, curable with chlorine gas, boron trifluoride, sulfur trioxide,hydrogen chloride gas, or boron trichloride; of the alkali metalsilicate type, curable with carbon dioxide. Particularly advantageousbinder materials are the aqueous alkali metal silicate materials havingan alkali metal silicate content of at least 10% by weight and asilica-to-alkali-metal-oxide weight ratio of 0.5:1-5.1. Such materialsinclude the aqueous sodium silicate materials containing at least 30% byweight sodium silicate and having an SiO₂ :Na₂ O weight ratio of atleast 2:1.

The binder material formulations are chosen to provide adequate plasticflowability to assure success of the pressing operation, and to retainthat characteristic for a period of time long enough to allow the bed ofsand mix to be established and advanced to the forming station.Typically, that period of time will be in the range of 1-15 min. Whenthe polymeric or silicate binder material employed is one which does notitself provide adequate characteristics, additional additives such ascereal flours, partially dextrinized cereal flours, wood flour, fireclay, bentonite, fine sand, bank sand, silica flour, and iron oxide canbe included.

When the binder material is an aqueous alkali metal silicate material,amounts in the range of 2-6% by weight, based on the weight of foundrysand in the mix, can be used. In general, amounts of binder materialemployed can range up to 10% based on foundry sand weight.

The initially continuous bed 2 of sand mix is advanced step-wise to theforming station 3, with each step of movement being adequate to bringthe leading end portion of the bed beneath the forming apparatus. Theshear box 6 is then forced downwardly into engagement with the conveyorbelt, with the result that a portion of the bed of sand mix is cut offfrom the main body of the bed and laterally confined by the shear boxand rigidly supported from below by the combination of plate 5 andbelt 1. Pattern 8 is then pressed downwardly into the confined sand mixto form the same into the shape desired for the finished mold part.

The pattern can be pressed into the bed of sand mix with pressuresranging from as low as 10 p.s.i. to as high as 150 p.s.i. (0.7-10.55 kg.per sq. cm.), depending upon the size, thickness and complexity of themold part to be produced. Particularly when using relatively highmolding pressures, e.g., 100-130 p.s.i. (7-9.1 kg. per sq. cm.) it isadvantageous to relieve the line pressure to the hydraulic pressingmotor before commencing the curing gas flow, since doing so minimizesany tendancy for the mold part to adhere to the pattern during curing.

The gaseous curing agent is supplied via bores 17 and 18 coincidentallywith completion of the pressing stroke, while the shear box 6 remains incontact with belt 1 and pattern 8 remains in engagement with the pressedsand mix and continues so engaged. A primary advantage of the inventionis that it allows very high rates of mold part production. Thus, forexample, using a sodium silicate type of binder, overall cycle times,i.e., the total time required to complete both the pressing operationand the curing operation and to then raise the pattern enough forremoval of the finished mold part, of as low as 8 secs. have beenachieved in making a mold part having a maximum thickness of 2 in. Forlarger mold parts, the invention provides significant advantages atcycle times up to, e.g., 65 sec. The total period of curing gas flowinto the pressed sand mix can be in the range of 4-60 sec., dependingupon the particular sand mix formulation and the size of the mold part.

Using a sodium silicate binder material at levels in the range of 2-6%of the foundry sand weight, and using commercial carbon dioxide gas asthe curing agent, the rate of consumption of CO₂, and therefore the rateat which the curing gas is supplied to the pressed mold part, can be inthe range of from about 2.5 to as much as 32 kg. per ton of sand mix,the upper limit being dictated by economics.

The following example is illustrative:

EXAMPLE 1

Using a conventional continuous foundry sand mixing apparatus, a sandmix comprising 3% aqueous sodium silicate, 2% partially dextrinized cornflour, and 0.5% water, based on the sand weight, was prepared. Thesodium silicate employed had an SiO₂ :Na₂ O weight ratio of 2.4:1, anNa₂ O content of 13.85% by weight, an SiO₂ content of 33.2% by weight, adensity of 52° Be., and a viscosity of 2,100 cps. The sand mix wasdelivered to a supply hopper located above the endless belt of anapparatus constructed according to FIGS. 1-4 and was delivered by thehopper onto the belt to form a continuous bed of sand mix approximately2.5 in. (6.35 cm.) in thickness. The endless belt employed was a 2-ply,center bound, untreated, woven, white cotton belt 0.24 mm. thick. Thebelt had an average weight of approximately 1.25 kg. per 30 meters oflength per 2.5 cm. of width. The shear box 6 of the apparatus hadinternal dimensions of 40.6 cm. transversely of the belt and 50.8 cm.longitudinally of the belt, so that the body of sand mix confined by theshear box had those plan dimensions. The main press was operated toforce the pattern downwardly into the confined sand mix with a pressureof approximately 9.1 kg. per sq. cm. at the face of the pattern, thefinished mold part having an edge thickness of approximately 5 cm.

Commercial CO₂ gas was employed as the curing agent, gas flow beingcommenced concurrently with completion of the pressing stroke andmaintained for 6 sec. while the shear box remained in place and thepattern remained engaged with the pressed mold part. Pressure in themain press cylinder was relieved to reduce the pressure on the patternduring gas flow. Gas flow was maintained at the rate of approximately16.5 kg. of CO₂ per metric ton of sand mix. At the end of the 6 sec.gassing period, the shear box and pattern were raised and the conveyoroperated one step to advance the mold part 26 to the position seen inFIG. 2 and present a new portion of the sand mix bed 2 at the pressingstation 3. The mold part 26 was found to be adequately cured forimmediate use in casting metal and was thus adequately hard and strongto be safely handled manually or by automatic equipment.

In some cases, it is advantageous to modify the method by heating thepattern to a temperature in the range of 110°-325° C., so that curing ofthe shaped surface of the mold part is accelerated. Maintaining thepattern at such an elevated temperature assures that the shaped surfaceof the mold part will be cured to a very hard condition even when thetotal cycle time is reduced, with the gassing time being only a fewseconds. Heating of the pattern is accomplished by providing horizontalbores in the pattern carrier of the press platen and insertingconventional electrical resistance type heating cartridges in the bores.In addition to improving the hardness and the precision of the shapedsurface of the mold part, heating of the pattern reduces any tendancyfor the mold part to stick to the pattern. The following example isillustrative:

EXAMPLE 2

The procedure of Example 1 was repeated, with the press platen equippedwith four electric resistance cartridge heaters operated to maintain thepattern at a temperature of approximately 200° C. The sand mix contained4.75% of the same aqueous sodium silicate employed in Example 1 and0.47% of a conventional catalyst for the sodium silicate binder, i.e.,the product marketed by Ashland Oil & Refining Co., Ashland, Kentucky,U.S.A., under the designation "Catalyst 3005". The total time ofengagement of the pattern with the mold part at completion of the downstroke of the press was 15 seconds and gassing with CO₂ was carried outfor the full 15 seconds at a pressure of 1.41 kg. per sq. cm. There wasno observable tendancy for the mold part to stick to the pattern, andthe finished mold part was found to be adequately cured throughout, butwith a shaped surface portion approximately 3 mm. thick being especiallyprecise and scratch-resistant.

Adequately cured mold parts, with especially hard shaped surfaces, areobtained when the procedure of Example 1 is duplicated precisely, butwith the pattern maintained at, e.g., 200° C. throughout the pressingand gassing steps.

THE APPARATUS OF FIG. 5

FIG. 5 illustrates the apparatus of FIGS. 1-4 modified to provide forgassing of the pressed mold part via bores in the pattern rather thanvia apertures in the supporting conveyor. The apparatus remains the sameas in FIGS. 1-4 except that platen 7 is provided with a plurality ofhorizontal bores 67 each of which communicates with a plurality ofvertical bores 68 in the body of the platen, bores 68 opening throughthe face of the platen which is to be engaged by the pattern. Pattern 58is provided with a number of vertical through bores 68a so arranged thateach bore 68a registers with a different one of the bores 68 when thepattern is properly mounted on the platen. The open end of each bore 67is connected to one of the conduits 19, FIG. 1, for supply of curing gasfrom the manifold. Bores 68a are packed, as with an expanded metalpacking, to prevent entry of sand.

The lower platen or support plate 5 can be solid, without gas supplymeans, or can be constructed in the same manner shown in FIG. 1, inwhich case the curing gas is supplied to the bottom of the pressed moldpart, in the manner described with reference to FIGS. 1-4, as well as tothe top of the mold part via bores 67, 68 and 68a.

THE APPARATUS OF FIG. 6

FIG. 6 illustrates a modification of the apparatus of FIGS. 1-4 whichprovides for supply of the curing gas via bores in the plate which formthe walls of the shear box. In the embodiment of FIG. 6, the apparatusremains the same as in FIGS. 1 and 2 except that the two side walls ofshear box 6 which are parallel to the length of the conveyor areprovided with a plurality of through bores 118 spaced apart over thearea of the respective side wall which is to engage the pressed moldpart. Each bore 118 is connected to one of the supply conduits 19, FIG.1, from the manifold, so that the curing gas is supplied directly to thetwo sides of the pressed mold part via bores 118. Bores 118 are packed,as with expanded metal packing, to prevent entry of sand.

All of the curing gas can be supplied via bores 118. Alternatively,support plate 5 can be constructed as described with reference to FIG. 1so that curing gas is also supplied upwardly through the conveyor belt,and the pattern can be constructed as described with reference to FIG. 5for additional supply of curing gas downwardly through bores in thepattern.

THE MODIFICATION OF FIG. 7

As illustrated in FIG. 7, flow of the curing gas to the pressed moldpart can be commenced automatically in response to completion of thepressing stroke. Thus, with on-off valve 22 being a conventionalsolenoid operated valve, energized-open, the solenoid of the valve isconnected to power terminal 30 via the normally open contacts of aconventional position switch 31 so located that its actuator is engagedby platen support 9 only at the end of the pressing stroke, with switch31 being actuated to its closed position, energizing the solenoid toopen valve 22, only when the down stroke of the press has beencompleted. In this embodiment, switch 31 remains closed, and valve 22therefore remains open, until the power device 32 of the press isoperated to raise the pattern carrier toward its inactive positionpreparatory to another cycle of operation.

It will be apparent to those skilled in the art that various changes andmodifications can be made in the method and apparatus, without departingfrom the scope of the invention as defined in the appended claims.

We claim:
 1. A method for producing foundry mold parts,comprisingpreparing a foundry sand mix comprising binder material whichcan be cured by a curing gas to render the mold part rigid; depositingthe sand mix upon an endless foraminous conveying member to form on theconveying member a bed of sand mix of predetermined depth; moving theconveying member to present a portion of the bed of sand mix at aforming station at a time when the sand mix is characterized by adequateplastic flowability for forming and the binder material retains a curingpotential adequate for rigidification of the formed mold part;supporting the conveying member and said portion of the bed of sand mixat the forming station and forming said portion into the shape desiredfor the mold part by pressing a pattern into said portion with apressure of 10-150 p.s.i. toward the conveying member while laterallyconfining said portion; passing a gaseous curing agent through theforaminous conveying member into the formed portion of sand mix whilethe pattern is in engagement therewith and said portion is stilllaterally confined and thereby curing the shaped mold part to at leastsuch an extent that the mold part can be moved and handled withoutbreakage or significant deformation; withdrawing the pattern from theshaped mold part so cured; and removing the mold part from the formingstation by advancing the conveying member beyond the forming station. 2.The method according to claim 1, whereinthe foraminous conveying memberis a perforated metal conveyor belt.
 3. The method according to claim 1,whereinthe foraminous conveying member is a woven fabric conveyor belt.4. The method according to claim 1, whereinthe binder material comprisesan alkali metal silicate material; the curing agent comprises carbondioxide gas; and said step of passing the curing agent into the portionof sand mix is carried out to provide to said portion of sand mix avolume of carbon dioxide gas equal to at least 2.5 kg. of carbon dioxideper metric ton of sand mix in a time period not exceeding 60 seconds. 5.The method according to claim 1, and further comprising maintaining thepattern at an elevated temperature of at least 100° C. during theforming step and the step of passing the curing agent into the portionof sand mix.
 6. The method according to claim 1, whereinthe pressure onthe pattern is relieved, without disengaging the pattern from the shapedmold part, before passing of the gaseous curing agent through theconveying member and the shaped mold part.
 7. In a foundry mold partmaking apparatus of the type comprising endless horizontal conveyormeans, means for depositing a foundry sand mix curable by a gaseouscuring agent and forming a continuous bed of the sand mix on theconveyor means, and means for driving the conveyor means stepwise toadvance the bed of sand mix toward a forming station in steps of equallength, the combination ofan endless conveyor belt forming the conveyingelement of the conveyor means,said belt being foraminous and capable ofpassing curing gas when the gas is applied to one surface of the belt;shearing and confining means mounted at the forming station for movementbetween an inactive position, in which movement of the sand mix bed isnot impeded by the shearing and confining means, and an active position,in which the shearing and confining means engages the conveyor andlaterally confines a predetermined portion of the sand mix bed; supportmeans located to rigidly support the combination of said portion of thesand mix bed confined by said shearing and confining means and theportion of the conveyor underlying said portion of sand mix bed,saidsupport means comprising a rigid member having a flat face over whichsaid belt runs; a vertically movable pattern carrier mounted at theforming station in alignment with said portion of the sand mix bedconfined by said shearing and confining means when the latter is in saidactive position; power means connected to said pattern carrier andoperable to move said pattern carrier toward said portion of the sandmix bed confined by said shearing and confining means to press thepattern into said confined portion and thereby form said portion of thesand mix bed into the shape desired for the mold part; conduit meansconnectible to a source of curing gas under pressure; and supply meansconnected to said conduit means for supplying curing gas to the formedportion of the sand mix bed while said portion is confined by saidshearing and confining means and engaged by the pattern carried by saidpattern carrier,said rigid member of said support means having internalflow means, to which said conduit means is connected, and a plurality ofdischarge apertures communicating with said internal flow means andopening through said flat face to supply curing gas to the lower surfaceof the foraminous belt.
 8. Apparatus according to claim 7, whereintheendless conveyor belt is a thin metal belt having a plurality of smallapertures; and said discharge apertures in said rigid member are largein comparison to the small apertures of the metal belt.
 9. Apparatusaccording to claim 7, wherein the endless conveyor belt is a woventextile belt.
 10. Apparatus according to claim 7, and furthercomprisingvalve means for establishing curing gas flow through saidsupply means; and means for operating said valve means to cause such gasflow only after said power means has been operated to cause said patterncarrier to move into a position such that a pattern carried thereby willhave formed the said severed portion of the sand mix bed into the shapedesired for the mold part.